Distributing external/street lighting

[YoungBart]

Afternoon all, I'm just working on the design of a large commercial property and they have requested external lighting, Which I have split into 3 areas, Back of house (deliveries, storage etc) Customer car park and staff car park area. I've got the lighting sorted to the requested levels which Is effectively my job over due to the nature of this job ,But I'm now wondering how It all gets distributed as I have very little knowledge of street lighting and the such.
My assumption is that from the main switchboard within the installation a feed gets taken to the external feeder pillar, in the pillar is a small 3ph DB for a few bits of external power, and then the DB/timeclock/controls for the lighting, set up just like a standard DB, Which would feed out to the lighting columns, Which would have a cut out within each column.
Am I on the right track or way off? It's not something I've had a lot of experience with.

Thanks in advance.
Jim

 

[malcolmsanford]

Most street light circuits I do would be as a ring main, and a good rule of thumb is a 16mm ring.

Remember when you calculate your VD you do it is sections so Panel to first light will be the total load, then a-b will be total load minus first first lamp etc etc, and you then add up the indiviual VD of each section to get the total,you can google the formula no doubt.

Also if your using typical lamp post columns and SWA 9 time out of 10 then will not be anywhere to terminate a SWA gland. Use the banjos with the lock nut and join the banjos with a brass 6mm nut, bolt washer and fly earth onto your fuse carrier/MCB holder

 

[Leesparkykent]

Most street light circuits I do would be as a ring main, and a good rule of thumb is a 16mm ring.

Remember when you calculate your VD you do it is sections so Panel to first light will be the total load, then a-b will be total load minus first first lamp etc etc, and you then add up the indiviual VD of each section to get the total,you can google the formula no doubt.

Also if your using typical lamp post columns and SWA 9 time out of 10 then will not be anywhere to terminate a SWA gland. Use the banjos with the lock nut and join the banjos with a brass 6mm nut, bolt washer and fly earth onto your fuse carrier/MCB holder

Or you could use a central earth terminal in the colum, they are designed for street lighting.

 

[Dave OCD]

You can also get a proper DP isolator/fuse carrier with a brass gland plate on the bottom specifically for SWA glands.

 

[YoungBart]

Thanks for the input guys, all interesting stuff, I didn't know about the alternative volt drop calc Malcolm How come it's different?
Am I correct in thinking each individual column has its own cut out, and then that circuit is backed up by a breaker of some sort.

 

[davesparks]

Thanks for the input guys, all interesting stuff, I didn't know about the alternative volt drop calc Malcolm How come it's different?
Am I correct in thinking each individual column has its own cut out, and then that circuit is backed up by a breaker of some sort.

For any circuit feeding multiple fixed loads you would calculate each stage separately for VD otherwise you end up with massive cables unnecessarily

 

[Flanders]

This is what you want lamp post cut outs 1 brand is called lucy https://www.google.co.uk/search?q=l...hWDWT4KHdQQBkUQ_AUIBygB#imgrc=GuwysQCd7e7ELM:

 

[YoungBart]

Thanks Davesparks, thought that might be the case, Ive never heard of a different system being used before.

I was looking at them earlier Flanders, they've got quite a helpful website for idiots like me :dizzy2:

 

[Sparkie30]

Mission terminating 16mm on those cut outs.

 

[GEOFF S]

Thanks for the input guys, all interesting stuff, I didn't know about the alternative volt drop calc Malcolm How come it's different?
Am I correct in thinking each individual column has its own cut out, and then that circuit is backed up by a breaker of some sort.

Hi

The method Malcolm sugests is suitable for a radial, a ring is a litlle different, you need to use kirchoffs current law,

Different parts of the cable will see differing levels of current dependent upon topology and load distribution.

As a rule of thumb, if you wire in a ring add a factor of 0.25 to th VD equation, if its a radial circuit factor is 0.5. If lighting is evenly distributed it will give very close results.

Cheers